Several different types of submersible light fixtures are available which are commonly used in water fountains to enhance the fountain display and in swimming pools to provide evening light. Sealed beam units are particularly effective for submersible lights. The sealed beam unit usually has a concave reflective surface made of glass and silver coated to reflect the light. The front face of the sealed unit is of glass and optionally has a face configured to provide either a focused or diffused type of beam. Submersible sealed beam units tend to be somewhat bulky in order to accommodate the size of the sealed beam. Unfortunately sealed beam units are not readiy available worldwide and in some instances, do not offer all voltage ranges which are used throughout the world, so that the design of submersible lighting units using sealed beams has been somewhat restrictive.
Other forms of submersible lighting involve standard incandescent light bulbs; however, they are of low intensity.
Another form of lighting, which provides high intensity, is the commonly referred to quartz-halogen type light bulb. These light bulbs are usually elongated or cylindrical in shape and are encased in a quartz bulb where the filament is emersed in a halogen gas. The output from these lights is of very high intensity; however, the lights operate at very high temperatures, such as 1700 to 1800 degrees F. In locating such lights in submersible fixtures, the reflective surfaces, which are commonly provided by a separate dish inserted into a housing, overheat. The reflective surface is burned off or discolored to the extent that the reflectivity is significantly reduced and thus the intensity of the light is lost.
Quartz-halogen lights have been used in swimming pool lights, where the housing for the light bulb is submersed in water to cool the housing. An example of such pool lights is the Model A400 fixture which may be obtained from PEM Fountain Company. This fixture has a truncated cone shaped housing in which the light is located. The heat from the light, in heating the planar truncated cone shaped surface, is dissipated by conduction into the pool water. The positioning of the light is fixed relative to the planar surface of the housing.
The submersible light fixture, according to this invention, overcomes the above problems in providing a compact light which is readily adjustable to vary the degree of light focus ranging from a spotlight to a floodlight.